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Message-ID: <5.1.0.14.0.20021126093630.02a65328@pb623250.kuleuven.be>
Date: Tue, 26 Nov 2002 09:51:32 +0100
To: rsgb_lf_group@blacksheep.org
From: "Rik Strobbe" <rik.strobbe@fys.kuleuven.ac.be>
In-reply-to: <DDC408CAE72CD511827A0002A5131CD6D9F851@exc_wil08>
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Subject: Re: LF: RE: loop antenna
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Hello Bill,


>First. Is 7mm the actual wire diam or the wire plus insulation?
7mm is de actual diameter, there is no extra isolation around the whole 
bunch of wires.

> >What distance should I keep to the ground ?
>
>I like 6 feet as the best compromise. The ground loss will amount to about
>1/2 of your total loss loss with a loop this size and conductor Rac this
>low. I'll give you a number later, based on my data.
OK, I'll keep the lower part 2m - 6ft8 from the ground for practical 
reasons (I'm 1m90 - 6ft4)

> >What distance should I keep to the greenery (birch trees)
>
>The trees will have almost no effect. I run my conductor (now a 1/2" Cu
>pipe, in full contact with the trees (see my loop website at
>http://www.ThePittsfieldInn.com/Bill/ for a picture of this), but it's a
>good idea to have some spacing at the lower portions of the loop where the
>voltage to ground is the highest. Also, you will have to protect the Litz
>wire from abrasion from the trees. That's a valuable piece of cable!
That sounds great, 'close contact' to the trees would allow me to increase 
the loop area from 300m^2 to 350m^2.

> >How to match the antenna ? As it is an experimental setup I would tend to
> >keep the resonance tuning (= series capacitor) and impedance matching (=
> >transformer) separated.
>
>DO NOT separate these components! This a very common mistake. The
>transformer and capacitor bank must be next to the loop feed point or the
>losses will kill you.
OK. I didn't mean to put them at different places, just to make resonance 
tuning and impedance matching independent of each other.
What I had in mind was something like fig.2b in your loop article 
(http://www.thepittsfieldinn.com/Bill/Loop1.htm)

73, Rik  ON7YD